Colored,transparent,durable titania films on glass



United States Patent 3,421,921 COLORED, TRANSPARENT, DURABLE TITANIA FILMS ON GLASS Albert E. Junge, New Kensington, and Joseph Chabal,

Curtisville, Pa., assignors to PPG Industries, Inc., Pittsburgh, Pa., a corporation of Pennsylvania No Drawing. Filed July 25, 1966, Ser. No. 567,388 U.S. Cl. 106-287 12 Claims Int. Cl. C09d 5/00 ABSTRACT OF THE DISCLOSURE A stable solution for coloring transparent glass articles without destroying their transparency. The solution is composed of a mixture of a hydrolyzable, organic titanate and a xanthene type dye. The presence of a copper salt in the solution improves the light fastness of the colored glass article. Salts of aluminum, lead, antimony and trivalent titanium stabilize the solution to prevent the titanate from precipitating from the solution.

The present invention relates to a coloring solution and it has particular relation to a coloring solution which can be used to apply a permanent color to a glass article.

It has long been a desideratum of the art to be able to dye or color glass articles after the glass has been melted, shaped and cooled to room temperature. It is well known that colored glass articles can be made by including ingredients in the glass batch that will color the glass 0 throughout. This method of coloring glass presents inventory problems when a plurality of colored glass articles are desired or where only portions of the article are to be colored. Low melting colored glass frits have been employed as coatings, but they are usually opaque and are unsatisfactory where colored, transparent articles are desired. Transparent metal oxide films which are developed on the glass at high temperatures have been employed, but the color selection is limited to the natural color of the oxide films. Typical patents illustrating such metal oxide films are U.S. Patents Nos. 2,584,763 and 2,593,817. Some attempts have been made to incorporate organic dyes on glass surfaces; however, problems of durability and light fastness have been encountered. For example, chrome complexes of various colorants have been applied to glass as shown in U.S. Patents Nos. 2,951,739 and 3,023,072, and British Patent No. 825,010. Colors that have the required light fastness usually have involved the use of opaque pigments or dispersed dyes. Where transparency is desired, pigments cannot be resorted to unless of colloidal dimensions.

In accordance with the present invention, a coloring solution for glass surfaces has been developed which is easy to apply and which results in the formation of a transparent, durable, tightly adherent colored film on the glass surface. The colored films exhibit unusual light fastness properties. The coloring solution is composed of a stable solution of the reaction product of a hydrolyzable organic titanate and an organic dye, preferably of xanthene type.

The exact chemical nature of the reaction product is not known; however, it is postulated that some type of chelate structure is created by the reaction. It is further postulated that the firm bond which is created between a silicate glass and the reaction product is the result of a silicon-oxygen-titanium bonding between the silicon of the glass and the titanium of the reaction product.

The formation of the coating solution is relatively simple. It merely involves preparation of a stable solution of the titanate and adding the dye to the solution. This can be done at room temperature and at atmospheric pressure. It is important that a solvent or carrier be selected that will permit the titanate to be uniformly dispersed in a stable form in the carrier. Thus the titanate is dissolved in the solvent or suspended as a very fine, clear, colloidal dispersion in the carrier. The term solution as used herein and in the claims is intended to include and cover both of such physical forms.

The preferred solvent for the titanate is methanol; however, the titanate can be employed in any liquid carrier or solvent that results in a stable solution, i.e., one in which the titanate does not precipitate out as a solid. Various stabilizing agents can be employed with the titanate solution if it exhibits unstable precipitating tendencies.

One titanate ester which has been found to be particularly suitable in the practice of the invention is tetraisopropyl titanate. Other useful titanates are those described in U.S. Patents Nos. 2,614,112, 2,621,195, 2,710,267, 2,768,909 and 2,941,903. These titanates have, for example, the formula (RO) Ti wherein R is an alkyl radical having from 1 to 18 carbon atoms, preferably 1 to 8 carbon atoms. The titanate solutions are described in these patents as being anhydrous. but having the possibility of the presence of a minor amount of water, such as a mixture of percent methanol and 10 percent water. Approximately 0.1 to 20 percent by weight of the titanate is useful in the. coating solution. The amount of titanate applied to the base is preferably about 0.0003 to 0.0375 gram molecule of ester per square meter of base surface. Such amount can be conveniently obtained by use of an anhydrous solution containing about 0.05 to 0.525 gram molecule per liter of solution.

Many organic dyes can be used in the practice of the invention. Best results have been obtained on massive glass articles such as fiat glass with xanthene class dyes. These dyes are derivatives of xanthene and are characterized by the presence of the xanthylium nucleus as the chromophore. Included in the xanthene class of dyes are the pyronines, sacchareins, succineins, rosamines, rhodamines, rhodoles and phthaleins, the latter being the preferred type. The chemical structures of xanthene and some derivatives found useful in the practice of the invention are as follows:

xanthene HO- \'=o no moa -o 0 on @[-o 0 ofluorescein (yellow) or (gold) Eosiu A (yellow-red) COOHa Eosine G (blue) COONa Rose Bengals (bluish-red) CH3 CH:

C O N8 Violamine R (blue) Rhodamine 6G Pyronine G Although the xanthene dyes have been found to be preferable in the tinting of flat glass, the invention is not limited to the use of such dyes especially with regard to the coloring of glass fibers. The tinting of glass fibers, in yarn or fabric form, is accomplished by the Xanthene dyes and many other dyes such as ketone imines, safranines, triphenylmethane amino derivatives, and diphenylnaphthylrnethane derivatives, examples of which are as follows \C/ II Auramine (yellow) Sairanine '1 (blue) l A S0411 Brilliant Green Wool Green The reason why glass fibers can be more readily dyed with a greater variety of dyes than flat glass is not known.

The amount of dye employed in the coloring solution is diflicult to state on a weight basis due to the complex nature of the variety of suitable dye molecules. In order to get maximum effectiveness of the dye, one mole of dye per mole of titanate can be employed. Substantially lower amounts of dye on a mole basis, i.e., 0.01 to 0.5 mole of dye to one mole of titanate are sufiicient to obtain good coloring. Lighter shades, of course, can be obtained by using a lesser amount of dye in relation to the titanate or by using a lower concentration of the reaction product in the solution. Furthermore, combinations of dyes can be used to get different colors and hues.

It has been found that certain properties of the finished article can be improved by the addition of certain metal salts to the solutions. For example, the light fastness of the colored article is improved by the inclusion of copper salts in the solutions, especially when the final product is exposed to liquid water. Copper sulfate (hydrated or anhydrous) copper halides, such as copper chloride (CuCl copper bromide (CuBr and copper fluoride (CuF copper acetate and copper nitrate have been used to improve the light fastness properties of the colored articles. About 0.1 to percent by weight of the copper salt based upon the weight of the coloring solution adequately serves this purpose.

The copper salts as well as some additional soluble salts serve the function of stabilizing the solution with respect to prevention of precipitation of the titanium ester from the solution. The soluble halides and nitrates of aluminum, lead, antimony and trivalent titanium aid in the stabilization of the coloring solution. About 0.2 to 15 percent by weight of these additional salts used alone or in combination based upon the weight of the solution adequately serve this purpose. It is important to state, however, that whereas copper salts stabilize the titanium ester in the solution, they also tend to precipitate the dye in the solution in the absence of aluminum salts; therefore, both aluminum and copper are usually employed in the solution. Gelatine can be used as a substitute for aluminum in this respect.

Use of the halides of the metals described above provides the best stability or shelf life to the coloring solutions. It has been found, however, that the halide solutions produce an objectionable degree of haze and loss of silver adhesion to the glass in mirrors. This haze and adhesion problem does not occur in the absence of halides and therefore it is concluded that the halide salts have some objectionable effect on the silver or the materials used in sensitizing the glass or catalyzing the silvering process. The reason for this is not known and is further obscured by the fact that the use of halongenated dyes, i.e., the halogenated fluoresceins (Eosin), does not create the haze effect. Use of the nitrates and sulfates of the above-mentioned metals in the coloring solutions avoids the haze in tinted mirrors.

Other materials which are useful for stabilizing the titanate in solution are acids such as citric and acetic acid and bases such as lithium, sodium and potassium hydroxide. Small amounts, of the order of 0.01 to 2.0 percent by weight of these materials, are useful.

The total amount of solids, i.e., titanate plus dye plus stabilizing agents, should not be more than 40 percent by weight of the solution, preferably not more than 20 percent by weight of the solution, in order to prevent precipitation of one or more of said solids from the solution.

The solution is prepared merely by adding the ingredients to each other and mixing them at room temperature. The solution can be prepared in glass containers or in plastic containers such as those made of polyethylene, polystyrene and polymethyl methacrylate. The solution should not be mixed in containers of copper, titanium, stainless steel, aluminum, brass, galvanized steel, Inconel, Monel or lead since these metals in contact with the solution cause precipitation of the dye.

The solution is applied to the glass article at room temperature. The application can be by dipping, painting or any other method convenient for applying a uniform coating of a liquid material.

The glass article may be in the form of fiat glass such as made by the commonly known plate, sheet or float processes. It may also be in pressed, centrifuged, attenuated, molded or blown glass form such as glass blocks, cathode ray tubes, fibers, tubing, ophthalmic and optical lenses, bottles and other for-ms. The term flat glass also includes glass articles made according to the above described processes and thereafter bent, shaped and/or laminated to produce fabricated glass articles. Such flat glass articles are made from conventional lime-sodasilica glasses. Opaque glasses such as milk glass and structural, fiat, white or ivory Carrara glass can also be tinted different colors and thereby solve an inventory problem. Such glasses are shown in US. Patent No. 2,683,616. The ophthalmic glasses are made from a variety of glasses, some of which may not contain any silica. Some of these glasses are shown in U.S. Patents Nos. 2,150,694, 2,542,489 and 2,913,345. Fiber glass is made from a borosilicate glass having a composition such as set forth in US. Patents Nos. 2,344,961 or 2,571,074. Examples of the compositions of various commercial glasses of the types above described are set forth in Tables IA-II (page 4), IA-III (page 5) and IIH-I (page 22) of the Handbook of Glass Manufacture by F. V. Tooley published in 1953 by Ogden Publishing Company.

Although it is theorized above that the bond with the glass is by an SiOTi linkage, it may be that the hydrolysis and condensation which apparently takes place in the bonding of the colored film to the glass surface merely involves reaction of the film of coating solution with tightly bound hydroxyl groups normally present on the surface of glass articles. This would explain the success of the invention with regard to the coloring of non-silicate glasses. This also permits application of the invention to the coloring of other materials normally having hydroxyl groups present on their surface or contained in the molecular structure of the material. One restriction is that the material to be colored can withstand the curing temperatures required (about 200 C.).

After application of the coating solution to the glass surface, the coated glass article is heated to bake or cure the coating on the glass. The heating step is necessary to develop the light fastness properties of the colored films. Exposure of the coated glass to temperatures of 400 F. to 500 F. for 60 to 10 minutes is satisfactory to accomplish the bonding of the coating to the glass. The curing treatment is time-temperature dependent and thus the exposure may be varied greatly depending upon the 7 8 production situation.For example, exposure of the coated During the filming of large glass plates, haze bands glass article to a temperature of 1250 F. for to seccan develop across the plate in a direction normal to onds is within the scope of the invention. The thickness the direction of withdrawal. These haze bands are deof the films produced is 200 to 5000 angstroms, prefertected only after the plate is silvered for mirrors. The ably 300 to 3000 angstroms. 5 theory of this haze development is that the evaporation Further details and embodiments of the invention can f t solvent during film forming absorbs heat from be explained and understood in the following examples; the surrounding air. Eventually the dew point of this air is reached. At this point, moisture from the air condenses EXAMPLE I on the film and this dries the air space. The lower part Flat glass plates 24 x 24 x A inches are dipped in the 10 of the plate enjoys a normal treatment. The top part of solutions set forth in Table I. The ingredients are added the plate escapes this haze effect because it is dry before and mixed in a suitable glass mixing container in the the dew point is reached. It is therefore desirable to withamounts listed and in the order listed in the table, bedraw the glass at a speed which is more than sufiicient ginning at the top of the table. No special mixing proceto overcome this effect. dure is necessary. The films are cured at 400 F. for 15 In the dipping process above described, the top inch or minutes. The films are approximately 500 angstroms so of the plate is uncoated. This portion can be easily thi k, cut off after the coating is cured on the plate.

TABLE I.--COl\iPOSITION OF VARIOUS TITANIA-DYE TINTING SOLUTIONS Methanol, cubic centimeters 100 100 1 0 100 00 100 100 100 100 100 100 100 100 AlCl fiH O, grams 1- 4 0 2.0 1.4 1.4

CuBr grams LiOH, grams H2O, cubic centimeters Tetraisopropyl titanate, cubic cen meters. Fluorcscein, grams Dibromotluorescein, grnms Eosin Y, grams l p A Color 1 Gold. 2 Flesh. 3 Red.

Some precautions are necessary during the dipping in EXAMPLE II.MIRRORS order to uniform 903mg on the flat g The Tinted mirrors are made utilizing solutions Nos. 5, 8 fiat glass 'P along Its top eflge by a.palr.of tongs and 12 from Table I to make respectively, gold, fiesh i glass is dlpped Into the coining solution In a Conand red tinted mirrors. Conventional plate glass samples, tamer. The descent of the glass 1s stopped short of com- 4 X 5 inches, are utilized The glass is Cleaned using a plete immersion of the glass so that the tongs and top 50 50 Weight percent Solution of Water and N propyl edge not enter the Solution necessary to prevent alcohol. The glass is then immersed vertically in the tint- Streakmg from runofi of the solunon m the top edge ing solution and withdrawn smoothly at a speed of 30 of the glass tongs upon wlihdrawal of the inches per minute. The film is decoated from one side glass. The glass 15 mamtamed 1n the solution for a length of the plate using a Wet Cloth The film prior to curing of time sufiicient for simple wetting of the glass surface by heat treatment is very Water soluble and easy to with 1:the solution. Dipping for a longer period than this 4? coat with water 18 I10 necessary- 0 The coated lass is heated to a tem eratur of 400 The withdrawal of the glass from the coating solutlon F for 30 Inmates and then allowed cool eslowly to is critical. The glass is withdrawn at a slow, steady rate, avoid breakace i film is now durable and ready for Le, 30 inches per minute. The film formation on the the silvering glass occurs as the coated glass rises from i l i The film is sensitized by rinsing it with a solution conand as the solvent evaporates from the coatmg clmgmg sisting in Weinht percent to the glass. Anything which changes the rate of evaporation during withdrawal is liable to cause streaks in the Ingredient Weight percent colored film on the surface of the glass which are dif- Water 50 ferent in appearance from the remainder of the film. Such Isopropyl alcohol 49 effect may be created by the occurrence of waves on the TiCl or SnCl 1 surface of the coating bath.

The effect may also be created by turbulence or uneven movement of air immediately above the solution bath thereby effecting change in the evaporation rate of the The final steps are accomplished according to the conventional mirror process. This includes silvering by exposing the sensitized film to the following solutions:

solvent as the glass is withdrawn from the bath. For this Silver Solution reason, it has been found desirable to enclose the area Innredient Pro Onions above the bath from the surrounding atmosphere in order "Silver nitrate 5 to eliminate the effects of stray currents of air in the Caustic ZITi': "Z," 5 factory. Such stray currents also affect the hum 1d1ty or Ammonium hydroxide (28% Solution) "Cc" 15 moisture cond1t1on of the air above the bath, WhlCll con- 5 H 0 m1 1000 dition is an important variable which affects the evapora- 2 u tion rate of the solvent. Likewise the temperature of the Reducer solution air above the bath should be controlled and not allowed Ingredient- Proportions to vary substantially in order to insure uniform evapora- Dextrose g 10 tion of the solvent from the coating. These precautions Water ml 1000 permit obtaining of films of uniform thickness which are free from iridescence. This is true with regard to films A copper coating and a protective paint backing are therehaving a thickness of greater than 500 angstroms which after applied.

are particularly subject to iridescence caused by thickness The mirrors are tested as described below with the renon-uniformity produced by conventional techniques. 7 sults being set forth in Table II.

9 l) Adhesion (pull test).This test consists of scratchcording to the following description of the invention. ing through the backing and film down to the base glass, Clear, etched, plate glass approximately 21 x 17 X A; applying Scotch tape over this area, then pulling off the inches in dimension was used. The glass is bent and then tape. Poor adhesion is signified by having the backing etched on both sides by a chemical etching process as and silver pulled from the glass with the tape. described in our pending application Ser. No. 456,963, (2) Salt spray.Mirror samples are subjected for 120 5 filed May 19, 1965. The etched plate is held by tongs hours to a percent salt spray. An evaluation is made from one corner and dipped in solution No. 2 set forth by noting the deterioration of the different samples. in Table I and withdrawn as described in Example I. The (3) High humidity.The samples are subjected for 60 convex side of the plate is washed clear of the coloring days in a 120 F. high humidity room, then checked for 10 solution with water and a wet cloth. The coated plate is deterioration. then cured at a temperature of 400 F. for 30 minutes. (4) Fadometer (Atlas Fade-Ometer).--Tinted mirror A durable gold film approximately 500 angstroms thick is samples are exposed in the fadometer, then checked for obtained on the concave side of the plate. The visible fade characteristics. transmittance of the plate measures 74 percent.

TABLE II.RESULTS OF VARIOUS TESTS OF TINTED MIRRORS Appearance 60 Days, Salt Fade-Ometer (hrs) Solution Seiisitizei' Prior to Pull Test 120 F. Spray,

Testing Humidity 120 his. 133 331 679 926 5 SnCl2 Good Good Good Good No Fade No Fade. No Fade. 5 TiCh do (1 do do do D0. 12 SnOlg "do-.. No Fade 12 'liCli do ..d0 do Fair+* do *Commercialiy acceptable.

EXAMPLE III. GLASS FIBER FABRICS The colored implosion plate is then laminated to the c face of the TV tube with a polyester resin by conventional is heat cleaned of an Sizino ingredients by first heating hered to the plastic interlayer. The visible transmittance it to F for 48 hours fabric is then cooled to of the colored, laminated plate measures 79 percent, an room tempsriature and dipbed in a Solution made up as increase of 5 percent over the unlaminated colored plate.

, This increase is due to the reduction in reflectance due giggi g; ig g? F g' EF fig gyg igi q are to the difference in the media adjacent the colored film.

The colored, coated plate as thus produced is useful and Color Dye esthetically pleasing as a TV implosion plate. The im- Red Eosin Y. plosion plate is especially useful in enhancing color con- Orange Fluor s intrasts in color television viewing.

Yellow Auranine 0. Purple Violamine EXAMPLE VI.-PICTURE GLASS Dark blue Safranin Tinted picture glass is made by dipping sheet lass into Dark green Du 9 antlhraqgmone green solutions No. 2 or 7. The sheet is withdrawn iertically Brown f' q i 7 40 from the bath at a speed of about 10 inches per minute. Grey German V10 e At this slower speed, a thinner film is applied to the major The dipped samples are heated for 30 minutes at 400 surfaces of the sheet. The thickness of film formed is pro- F. to cure the colors on the fabric. The dyed fabrics eX- portionate to the withdrawal rate and thus a thinner film hibit excellent light fastness and film durability. is formed at the slower speed. The film is then cured at EXAMPLE IV OPHTHALMIC LENSES 400 F. for 30 minutes A durable, lightly tinted, uniform colored film having a thickness of 400 angstroms is present Various s mpl s of P011811ed Ophthalmlc lenses are on the sheet. The sheet, coated with solution No. 2, is tintcoated with So uti l 9 from Table to apply a flesh ed gold and has a transmittance of 80 percent. The sheet, tint t0 t glass lfmses for Ophthalmlc purposes- The coated with solution No. 7, is tinted flesh color and has a lenses are recessed in a rubber Sheet to Protect the edges transmittance of 80 percent. The films withstand cleaning and laid on a conveyor which carried them at a rate of with any type of liquid glass cleaner,

about 30 inches per minute into and out of a bath. The

following glass compositions are tinted: EXAMPLE VII.-OPAQUE STRUCTURAL PANELS TABLE III Various colored opaque, structural, flat glass panels are Composition made from a commercial, white opaque, structural glass Ingredi 1 2 3 4 5 having an approximate composition in percent by weight exit as follows:

Ophthalic Ophthalmic Optical; Boiosilicate Spectacle Flint Crown Crown Percent SiO 67 5 Nazo 8 6 K 0 3 3 C210 10.6 A1 0 6.01

F2 u a 5.7

0.1 Minor constituents 0.6

The panels are treated with coloring solutions by dip- 70 ping them in the solution in the manner described in 1 tinted with the flesh c0101. b use f Example I with a solution made according to the method i z iz g g in Table I y described for solutions Nos. 6, 9 and 13 in Table I. The following colors are obtained by using the specified EXAMPLE V-TV IMPLOSION PLATE amounts of the listed dyes. The films are durable and ex- A tinted TV implosion plate is made and utilized achibit excellent light fastness.

ll 12 Color: Dye 4. A method of coloring a glass article which com- Gold Fluoresc in. prises applying to the surface of the glass article a thin Flesh Dibromofiuorescein. coating of the solution described in claim 1 and heating Red Eosin Y. the coated article for a time and at a temperature sufficient to develop light fastness properties to the colored glass article. 5. The method of claim 4 utilizing the solution com- Commerclfil glass fiber Y deslgnalefl as 1501/ prising a stable solution of the reaction mixture of hy- IZ is Permanently y y the Present lnvfintlon by P drolyzable, organic titanate and a xanthene dye with a ing either the yarn or a fabric through a bath containing Solids content f not more than by Weight of the the coloring solution and thereafter heat treating the 001- solution Containing a light stabilizing amount f a EXAMPLE VIII.GLASS FIBER YARNS ored yarn or fabric to fix the color permanently in the persalt Colored Product Thfi Y 1S colored lndlvlduflny or as 6. The method of claim 5 wherein the solution addi- PP 011 a q filled (lulu pp tionally contains a solut1on stabilizing amount of an 1nmg solut1on and 18 then heated in a furnace maintained at 15 Organic lt le ted f om the group consisting of the o 400 F- f rnmutes to cure the coating n the y soluble salts of aluminum, lead, antimony and trivalent The (1) cond1tion of glass sample, (2) solutions utilized, tit i (3) dyeing conditions and (4) heat treating employed in 7. A colored glass article produced according to the the various tests are shown in Table IV. method of claim 4.

TABLE IV Dye Solutions Heat Treatment Example 6. Sample Table I with Dye Application Finish Color Dye Listed Temp, F. Time Below 1. Coronized yarn Fluoreseein 17 feet per minute 4.30 seconds..." None Orange.

through bath. 1. Coronized yarn do 70 feet per minute 450 12 seconds...

through bath. 3. Wound on quill, starch-oil .do Quilts soaked for 450 30 minutes size. 30 minutes. 4. Wound on quill, acrylic .do do 450 do ..do

size. 5. Wound on quill, polydo do 400 .do do..

vinyl acetate size. 6. \Vound on quill, epoxy .do .do 450 .do .d0

size. 7. Cornnized yarn Violamine lllll 17 feet per minute 450 50 seconds "do"...

through bath. 8. Coronized yarn do do 450 25 seconds... Acrylic emulsion plus another Do.

heat treatment, 17 feet per minute. 9. Coronized yarn do 70 feet per minute 450 6 seconds Acrylic emulsion plus another Blue.

through bath. heat treatment, 70 feet per minute. 10. Conroized yarn do "do 450 1'2 seconds.. None Reddish purple. 11. Wound on quill, epoxy do Quill soaked for 400 30 minutes .do Light violet.

size. 30 minutes. 12. Wound on quill, epoxy .do .do Acrylic emulsion at 17 feet per D0.

size. minute plus heat treatment of 400 F. for 30 minutes. 13. Coronized yarn Croccin searlet- 17 feet perminute 450 30 minutes None Light tan.

110 through bath. 14. Coronized yarn ..do ..do 450 15 minutes Acrylic emulsion at 17 feet per Do.

minute plus additional heat treatment. 15. Coronized yarn Safranin O .do 450 30 minutes... None Violet. 1o. Coronizcd yarn .do "do 450 15 ininutes Acrylic emulsion at 17 feet per Dark violet.

minute plus additional heat treatment. 17. Coronizcd yarn Auraniinc O ..do 450 30 minutes"- None Light gold. 18. Coronized yarn ..do do 450 15 1ninutes Acrylic emulsion at 17 feet per Yellow tan.

minute plus additional heat treatment.

NOTE.-C0l'0ili7.0(l is a term which is applied to yarn (or fabric) which is passed through a furnace maintained at l,150 F. to remove the size and heat. set the individual nbers if they are woven or otherwise entwined.

The present invention has enabled the production of a 8. Colored glass fibers produced according to the plurality of colored glass articles by a novel coating method of claim 4. method. The invention is particularly unique in that 9. A transparent, colored glass article produced accolored articles are obtained which exhibit excellent light cording to the method of claim 4. fastness properties with organic dyes which are no- .10. A transparent, colored flat glass article produced toriously poor with respect to this property when preaccording to the method of claim 4. viously used. 11. A colored glass article produced according to the Although the invention has been described with remethod of claim 5. spect to details of the best modes of carrying out the 12. A colored glass article produced according to the invention presently known to the inventors, such details method of claim 6. are not intended to serve as limitations on the scope of References Cited the il'lVBilflOl'l, except as set forth in the following claims. UNITED STATES PATENTS We calm 2,139,471 12/1938 Schmidt 260-4295 1. A coloring solution comprising a stable solution of the reaction mixture of a hydrolyzable, organic titanate 2,345,482 3/1944 Kfzlkalla 260-41295 and a xanthene type dye with a solids content of not 2,452,600 11/1948 Slegel 106-300 more than 40% by weight of the solution. 2,492,959 1/1950 Blllmenthal 260336 2. The solution of claim 1 containing a light stabilizing 7 0 amount of a copper SHIL JULIUS FROME, Primary Examiner.

3. The solution of-claini 2 containing a solution sta- T. MORRIS,AssistantExami/wr. bilizing amount of an inorganic salt selected from the group consisting of the soluble salts of aluminum, lead, U.S. Cl. X.R.

antimony and trivalent titanium. 

